This application relates generally to gas turbine engine rotor assemblies and, more particularly, to bearing assemblies for gas turbine engine rotor assemblies.
Gas turbine engines typically include a fan rotor assembly, a compressor, and a turbine. The fan rotor assembly includes a fan that includes an array of fan blades extending radially outward from a rotor shaft. The rotor shaft transfers power and rotary motion from the turbine to the compressor and the fan, and is supported longitudinally with a plurality of bearing assemblies. Bearing assemblies support the rotor shaft and typically include rolling elements positioned within an inner race and an outer race. The outer race is radially inward from a sump housing.
As the rotor is accelerated, non-synchronous vibration may develop within the rotor assembly and be induced to the bearing assemblies. Continued exposure to vibrational forces may result in premature failure of the bearing assembly. To minimize potential detrimental effects associated with such vibrations, at least some known gas turbine engines include a damper assembly adjacent the bearing assemblies to control rotor motion associated with non-synchronous vibration. The damper assembly is positioned such that a radial clearance is defined between the bearing assembly outer race and the damper assembly to facilitate minimizing vibrational forces being induced from the bearing assembly into the mounting frame. Because the clearance is typically pre-set based on geometric tolerances and thermal growth considerations, partial part distortions may affect the damper clearance and may result in rotor motion that is not damped.
In an exemplary embodiment, a rotor assembly for a gas turbine engine includes a bearing assembly and a damper sub-assembly that facilitates reducing dynamic motion of the rotor assembly. The bearing assembly includes a plurality of rolling elements positioned between an inner and an outer race, and a plurality of springs that couple the bearing assembly to a sump housing. The sump housing extends between a damper insert and a combustor casing. The rotor assembly includes a rotor shaft supported by the bearing assembly and rotatably coupled to the bearing assembly inner race. The damper sub-assembly includes the damper insert which is coupled within the engine radially outward from the bearing assembly.
During operation, as the rotor shaft rotates, the sump housing distorts causing the damper insert to distort against the sump housing. The damper sub-assembly facilitates reducing dynamic motion of the rotor assembly. Specifically, the outer race deflects to substantially match a distortion pattern of the damper insert distorting against the sump housing, such that a variation in a clearance defined between the bearing assembly and the damper insert is facilitated to be reduced. More specifically, a portion of the bearing assembly outer race in contact with the roller elements deflects to match the distortion pattern of the damper insert. As a result, the bearing assembly and the damper sub-assembly facilitate reducing dynamic motion of the rotor assembly.